Supporting insulator for electrical heating elements

ABSTRACT

The insulator consists of a body of triangular shape pressed from refractory material and having a non-circular aperture for receiving the heater element. The outer surface of each side of the body is formed with a pair of projections spaced apart axially of the body. Preferably the projections of each pair are located adjacent the apexes of the triangular body and whereby the projections of each pair are also spaced apart in a direction lengthwise of each side.

' [72] Inventor:

United States Patent Alexander [54] SUPPORTING INSULATOR FOR ELECTRICAL HEATING ELENIENTS Donald E. Alexander, Knoxville, Tenn. [73] Assignee: Carrier Corporation, Syracuse, NY. [22] Filed: June 23, 1971 [21] Appl. No.: 155,953

[52] U.S.Cl. ..l74/138J, 219/532, 219/546,

- I 338/317 [51] Int. Cl. ..H0lb 17/58, HOlc 1/02, H05b 3/06 [58] Field ofSearch ..174/1'38 J, 152 G, 153 G, 154;

[56] References Cited UNlTED STATES PATENTS 1,820,696 8/1931 Forshee 1 74/152 G [451 June 6,1972

Averill et al. ..338/317 X FOREIGN PATENTS OR APPLICATIONS 9,478 1893 Great Britain 174/154 Primary ExaminerLaramie E. Askin Attorney-Harry G. Martin, Jr. et al.

[57] ABSTRACT The insulator consists of a body of triangular shape pressed from refractory material and having a non-circular aperture for receiving the heater element. The outer surface of each side of the body is formed with a pair of projections spaced apart axially of the body. Preferably the projections of each pair are located adjacent the apexes of the triangular body and whereby the projections of each pair are also spaced apart in a direction lengthwise of each side.

6 Claims, 4 Drawing Figures Himes ..174/138 .1

' heating 1 SUPPORTING INSULATOR FOR ELECTRICAL HEATING ELEMENTS BACKGROUND OF THE INVENTION In many forms of electrical heating apparatus the heating element as, for example, a helical coil of resistance wire, is

annular form with circular apertures. Of necessity the insulators must be of sufiicient axial length to bar current leakage from the bare or uncovered type of resistance element to the supporting metallic grille work. With insulators formed with round apertures for reception of the round heating elements, a substantial area of the circumferential surface of the element is in contact with the wall surface of the insulator aperture, or is positioned in close proximity thereto. Accordingly, the heat produced by that portion of the element within the insulator is not dissipated sufficiently to prevent the element from becoming overheated, and thereby materially reducing the normal life expectancy of the element.

Attempts have been made to solve that problem as by enlarging the aperture in the insulator at the ends thereof, leaving an internal circular ridge of small axial dimension in the center of the aperture. Also, insulators have been formed with projections extending inwardly from the wall of the aperture. Arrangements of this type are not desirable in that they do not provide sufficient supportfor the heating element and add to the expense of making the insulator and add to the difficulty of threading the heating coil through the insulators.

This invention has as an object a heater coil insulator having a form whereby the insulator is produced from ceramic refractory material by a pressing operation with a die and core of simple form, the side wall of the aperture of the insulator being non-circular and being free from projections, and being of uniform dimension providing ample space between the element and the side wall of the aperture for adequate circulation of air between the heating element and the insulator to prevent over-heating of the heating element.

SUMMARY OF THE IN VEN'TION The insulator is of triangular shape and is formed with a non-circular aperture, also preferably of triangular form, for

the reception of the heater coil. The outer surface of each side of the-body is formed with integral projections spaced apart in a direction axially of the insulator. The projections are preferably located adjacent the apexes of the insulator whereby the projections of the pair on each side of the insulator body are also spaced apart in a direction lengthwise of the side surface of the insulator.

BRIEF DESCRIPTION OF THE DRAMNG DESCRIPTION OF THE PREFERRED EMBODIMENT The insulator is of triangular form having side walls 10, 11,

' 12 and is also formed with a triangular shape aperture extend- I supported by being threaded through a plurality of apertured ing axially through the insulator. The side walls 10-12 meet at the apexes of the insulator on an external radius 13 and an internal radius 14. This configuration is clearly shown in FIGS. 1 and 3.

' provided with projecsrde wall are spaced apart in a direction axially of the insulator, as shown in FIGS. 2 and 4, providing a space indicated by dash lines 24, FIG. 2, for the reception of a mounting member l0, 12 as shown in FIG.

The projections 15-23 are all complemental in shape and dimension, and the projections of a pair on a side wall are also shown in the drawings.

The metallic grille work for supporting the insulators is completed by a linear rod mediate certain adjacent insulators,

as by spot welding, such areas being indicated at 31, FIGS. 3 and 4.

The insulator coil element is indicated at 35 on the drawings ring to FIGS. 1 and 3 that the heating coils 35 have substantially only line contact with the inner sides of the triangular aperture in the insulator body. There is accordingly a substantial inner apex area, indicated at 37, for the circulation of air through the insulator and about the heating element 35, effecting sufficient dissipation of heat to prevent the heating element 35 from becoming overheated in the area of the insulasupporting grille work 25, 27.

The projections 15-23 are of semicircular form which greatly simplifies the machining of the forming die. Also, such shape avoids warping of the insulator during the firing thereof.

I claim:

1. An electrical heater coil supporting insulator comprising a body of triangular shape formed with an aperture of non-cirform extending lengthwise through the body for recepdirection lengthwise of the body.

2. An insulator as set forth in claim 1, wherein the projections of each of said pairs are spaced apart in a direction lengthwise of said side surface.

3. An insulator as set forth in claim 1, wherein said aperture is of triangular form.

4. An insulator as set forth in claim 1, wherein said aperture is of polygonal fonn.

5. An insulator as set forth in claim 1-, wherein said projections are located adjacent the apexes of the body.

6. An insulator as set forth in claim 1, wherein said projections are of semicircular form. 

1. An electrical heater coil supporting insulator comprising a body of triangular shape formed with an aperture of non-circular form extending lengthwise through the body for reception of the heater coil, said body being formed of heat refractory insulating material, the external surface of each side of said body being formed with a pair of integral projections, the projections of each of said pairs being spaced apart in a direction lengthwise of the body.
 2. An insulator as set forth in claim 1, wherein the projections of each of said pairs are spaced apart in a direction lengthwise of said side surface.
 3. An insulator as set forth in claim 1, wherein said aperture is of triangular form.
 4. An insulator as set forth in claim 1, wherein said aperture is of polygonal form.
 5. An insulator as set forth in claim 1, wherein said projections are located adjacent the apexes of the body.
 6. An insulator as set forth in claim 1, wherein said projections are of semicircular form. 